I never got around to replying to this until now, sorry..

On Mon, 4 Nov 2002, Bob Hinden wrote:
> A lot of the discussion seems to imply that site-local addresses are 
> created automatically (like link-local).  This is, of course, not the 
> case.  Site-local are only created if someone configures a router with a 
> specific site-local address on an interface and tell the router to 
> advertise the prefix in a routing protocol to other routers and to 
> advertise it to hosts on the link in RAs.  Site-local addresses will only 
> appear in a site if an administrator decided to configure them.
 
Anyone can just blindly configure a site in one link.  Not much of a site, 
but you can use site-locals, and you can source traffic from site-local 
addresses..

> It seems to me that from a reachability point of view there isn't too much 
> difference between using site-local addresses and having a firewall that 
> blocks traffic from one set of global addresses and another.  Firewalls 
> create limited scope addresses from global addresses.  

Note that a third option is to use global addresses (assuming the site has 
them), a part of their block, but no route it externally at all.   And add 
firewall filters besides.

> If one assumes the 
> existence of IPv6 firewalls, then these firewalls can also enforce site 
> boundaries.  

Sure, but that is not sufficient to satisfy addr-archv3 2.5.6 last 
paragraph IMO.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords

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